1. Field of the Invention
The present invention relates to a drying device for drying a wet image recording medium.
2. Description of the Related Art
In recent years, printing devices utilizing a digital exposure, namely, digital photographic printers, have been put into practice. The digital photographic printer is a device in which an image recorded on a film is read in a photoelectric manner, the read image is converted to digital signal, the digital signal is subject to various image processings to obtain image data for recording, an image (a latent image) is formed on a photosensitive material by scanning and exposing the photosensitive material with a recording light modulated in accordance with the image data, the photosensitive material is subject to developing processing, and a print (a photograph) is output.
A processor included in the digital photographic printer described above is provided with a developing section and a drying section. The developing section performs the developing processing in which the photosensitive material on which the latent image is formed is immersed in a developing tank. The drying section dries the developed photosensitive material.
A structure of the drying section for drying the photosensitive material thereat is well known in which a hot (warm) air is blown to the conveyed photosensitive material. Also, in recent years, a structure of the drying section in which radiation heat is utilized to improve a drying speed of the photosensitive material is proposed.
It is a disadvantage of the structure of the drying section in which the warm air is blown to the photosensitive material described above that drying efficiency is low because large amount of heat losses, from a side surface of a duct providing the warm air, to the outside.
When the drying section is structured such that the radiation heat is also utilized, it is necessary to provide both a section for drying in which the warm air is blown and a section for drying in which the radiating heat is utilized, at the drying section. Accordingly, It is a disadvantage that the drying section becomes large.
Moreover, when the drying section is structured such that the radiation heat is utilized, it is proposed that material which has high emissivity and high thermal conductivity is applied to a conveying system of the drying section. However, because this conveying system is heated by the warm air, the radiation heat is not used actively.
Moreover, there is another problem that unevenness of drying state of the photosensitive material may occur due to blowing positions of the warm air not existing appropriately.
The present invention was developed in order to overcome the above-described drawbacks, and an object of the present invention is to provide a drying device which can perform drying efficiently without enlarging the drying device.
In order to achieve the above object, an image drying device of a first aspect of the present invention is a drying device for drying a wet image recording medium conveyed along a conveying path, comprising: a plate member disposed along the conveying path, the plate member including blowing holes through which a wind for drying is blown onto the image recording medium and facing the conveyed image recording medium; and a heating device for directly heating the plate member, the heating device being disposed on or inside the plate member.
In an image drying device of a second aspect of the present invention according to the first aspect, at least a surface, which faces the image recording medium, of the plate member comprises a material having high emissivity.
A drying device of a third aspect of the present invention is a drying device for drying a wet image recording medium conveyed on a conveying path, comprising: a plate member disposed along the conveying path, the plate member including blowing holes through which a wind for drying is blown onto the image recording medium and facing the conveyed image recording medium; a first heating device for directly heating the plate member, the heating device being disposed on or inside the plate member; and a second heating device disposed at a wind for drying supplying path for supplying the wind for drying to the blowing holes of the plate member, wherein the wind for drying is heated by both the first heating device and the second heating device.
In an image drying device of a fourth aspect of the present invention according to anyone of the first aspect through the third aspect, the device further comprises a conveying member for conveying the image recording medium, the conveying member facing the plate member and being disposed such that the conveyed image recording medium is interposed between the plate member and the conveying member, wherein the image recording medium is conveyed in a state in which an image recording surface of the image recording medium faces the plate member, and the image recording medium is conveyed in a state in which the image recording medium is pressed in a direction of the conveying member by one of wind pressure of the wind for drying blown from the blowing holes and negative pressure of a blowdown side of the wind for drying, such that the image recording medium does not surface-contact the plate member.
In an image drying device of a fifth aspect of the present invention according to anyone of the first aspect through the fourth aspect, at least one rib is provided at a surface, which faces the image recording medium, of the plate member, the rib extending both downstream in a conveying direction of the image recording medium and laterally in a width direction, from a substantial center of the plate member toward a substantial width-direction edge of the plate member, the width direction being orthogonal to the conveying direction.
In an image drying device of a sixth aspect of the present invention according to anyone of the first aspect through the fifth aspect, portions of blowing holes which are located in different positions in a conveying direction of the image recording medium and which are adjacent in a width direction of the plate member when viewing along the conveying direction, are overlapped.
In an image drying device of a seventh aspect of the present invention according to anyone of the first aspect through the sixth aspect, an opening rate of the blowing holes with respect to the plate member is equal to or more than 2% and equal to or less than 10%.
In an image drying device of an eighth aspect of the present invention according to anyone of the first aspect through the seventh aspect, a temperature sensor is disposed at the plate member.
The first aspect of the present invention will be described in detail.
Because the plate member is disposed at the position in which the plate member faces the image recording medium along the conveying path, and the heating device heats directly the plate member, the conveyed image recording medium is dried by a radiating heat of the heated plate member. At the same time, the wind for drying (a warm air) which is from the blowing holes formed on the plate member and which is heated by the heating device, is blown onto the image recording medium. Accordingly, the image recording medium can be dried further efficiently.
In particular, because the heating device heats directly the plate member, amount of the radiating heat can be made large. Therefore, drying speed (drying efficiency) can be improved. Further, because the wind for drying is heated by the heated plate thereby be a warm air, it can be suppressed that the warm air is cooled due to heat loss or the like from a duct by the time when the warm air reaches to the blowing holes. Also, a portion to be heated (heat capacity) is made relatively small. Accordingly, a time necessary for heating can be reduced. Further, in the present invention, the radiating heat of the plate member in which the blowing holes are provided is utilized, the radiating heat and the wind for drying can be utilized at a same portion, therefore, the enlargement of the device can be suppressed.
The second aspect of the present invention will be described in detail.
Because at least the surface, which faces the image recording medium, of the plate member is formed by the material having high emissivity (a total emissivity is equal to or more than 0.9), the radiating heat is transferred from the plate member heated by the heating device to the image recording medium efficiently. Accordingly, drying efficiency of the image recording medium can be improved.
The third aspect of the present invention will be described in detail.
Because the first heating device is provided at the plate member and the second heating device is provided at the wind for drying supplying path for providing the wind for drying to the blowing holes of the plate member, and the wind for drying is heated by both the first heating device and the second heating device, a temperature of the wind for drying can be made high efficiently. Accordingly, drying efficiency of the image recording medium can be improved.
The fourth aspect of the present invention will be described in detail.
The image recording medium which has reached to the drying device is conveyed in the state in which the image recording surface of the image recording medium faces the plate member. At this time, the image recording medium is conveyed in the state in which the image recording medium is pressed toward (and abutted on) the conveying member which is disposed to face the plate member, namely, in a state in which the plate member is apart from the image recording medium, by the wind pressure of the wind for drying blown from the blowing holes of the plate member or the negative pressure of the blowdown side of the wind for drying. Accordingly, it is prevented that the image recording medium is conveyed in a state in which the image recording medium slides with respect to the plate member by surface-contacting each other. Accordingly, it can be surely prevented that the image recording surface of the image recording medium is damaged.
The image recording medium may be made curled in the width direction which is orthogonal to the conveying direction in accompany with being dried, and therefore, the end portions of the image recording medium may abut the plate member. However, even when the end portions of the image recording medium in the width direction abut (line-contact) the plate member, the image recording surface of the image recording medium cannot be damaged.
The fifth aspect of the present invention will be described in detail.
The image recording medium being conveyed in the drying device may be made curled in the width direction which is orthogonal to the conveying direction in accompany as being dried. As a result, tip ends of the both end portions in the width direction of the image recording medium (hereinafter, tip corners) may slide on the plate member. At this time, it may happen that the tip corners enter the blowing holes formed in the plate member and the tip corners are damaged, and/or the image recording medium is jammed.
However, in this aspect, because at least one rib (protrusion) is provided at the surface, which faces the image recording medium, of the plate member, such that the rib extends toward the downstream side of the conveying direction of the image recording medium, from the substantial central portion of the plate member in the width direction which is orthogonal to the conveying direction, to the substantial end portion of the plate member in the width direction, the tip corners abutting the plate member are guided by the protrusions to move toward respective end portions of the plate member. Namely, the curled image recording medium is made to be plane by the protrusions. Therefore, an angle of the tip corner with respect to the plate member is made small. Accordingly, a possibility that the tip corners enter in the blowing holes can be reduced. Accordingly, the damaging of the image recording medium and/or the jamming of the image recording medium can be suppressed.
The sixth aspect of the present invention will be described in detail.
The blowing holes are disposed such that the portions of blowing holes located in different positions in the conveying direction of the image recording medium and neighboring each other in the width direction of the plate member when viewing along the conveying direction, are overlapped.
Namely, blowing holes are aligned in columns substantially orthogonal to the conveying direction, with blowing holes in respectively adjacent columns being offset in the conveying direction, such that blowing holes in respectively adjacent columns would partially overlap if a column were to be superimposed on an adjacent column in the conveying direction.
Accordingly, as the image recording medium is conveyed on the conveying path, the wind for drying can be blown onto the image recording medium in entire area in the width direction without non-uniformity. Therefore, unevenness of amount of the wind for drying blown onto the image recording medium in the width direction can be suppressed. Therefore, unevenness of drying state of the image recording medium can be suppressed.
The seventh aspect of the present invention will be described in detail.
The drying efficiency of the image recording medium by the wind for drying depends on a wind velocity of the wind for drying. In this aspect, the opening rate of the blowing holes with respect to guide plate is equal to or more than 2% and equal to or less than 10%. By this structure, the blowing speed (wind velocity) of the wind for drying is equal to or more than a predetermined value, the drying efficiency of the image recording medium can be improved.